The Snake and the Demon
by LordAnthony2299
Summary: Koyomi has finally accepted Sengoku's invitation. Her trap is set and everything is planned... but she didn't account for a girlfriend. Senjougahara's jealousy proves uncontrollable as Koyomi and Sengoku's relationship deepens. Rated M for safety (but probs no M stuff till much later)


**The Snake and the Demon**

 **AN: Hello there readers, this is my first fic and I'd really like some constructive criticism to get me going, I'm really new to this crap and have just been going through other fics to grasp the basic formatting so please understand if you see any noticeable fuck-ups and inconsistencies. All I have for editing are shitty friends who laugh at all this crap. So anyway I've recently gotten into Monogatari and adore Sengoku so this is probably going to turn out as a Koyomi x Sengoku fic (even though I have no real direction for this fic in the first place). Any feedback would help me immensely. Cheers :D**

 _Italics_ **\- Thoughts**

Bored. That was all that Koyomi Araragi felt on this particularly dull Saturday morning. Hanekawa had cancelled their normal tuition which to most would be cause for celebration, but for Koyomi this meant his day would only be occupied by bickering little sisters and *ahem* 'taking care of himself.' Stealing looks at Hanekawa's chest also had a certain... therapeutic effect, something Koyomi had been readily looking forward too. But of course it was education (and boobs) that was first on Koyomi's mind (mostly the boobs).

Realizing the tedious day he had ahead of him Koyomi trudged down the stairs from his room to find his little younger sister sprawled on the couch watching TV in her short green kimono. He didn't particularly feel like chatting with this explosively moody little shit.

 _Maybe if I sneak by I can avoid any conversa-_

'Oh, Koyomi-oniichan don't you have your tutoring today?' Tsukihi Araragi announced, turning off the television and rising to greet her older brother.

 _Shit._ He cursed under his breath and turned to face his sister with a pained expression.

'Yeah' He didn't feel as if he had to explain anything to her, but... something was wrong with this picture. Last time he checked he had two younger sisters to account for whereas only one little shit was staring him in the face right now.

'Where is she' He inquired, venom in his voice

'She?' Tsukihi mockingly asked, cocking her head

'The bigger little sister' _Literally,_ Koyomi thought inwardly now standing noticeably taller than him, a large mental sigh of dismay playing in his mind.

'Karen-chan's out'

When Koyomi heard this he immediately thought, no, knew that one half of the Fire-Sisters was terrorizing the town.

The conversation quickly devolved into the normal bickering and brother-sister spat that Koyomi had grown so accustomed too. 'Don't get into trouble playing your damned game' he'd always say, which would almost always result in a 'You always treat us like kids' response from one of the two little shits.

'Stay out of middle school fights Koyomi-Oniichan, it's kind of pathetic. In it's own way fighting is a way of communication'

'Anything you little bastards do is violent, I refuse to believe your way of fighting is right'

As soon as this slipped free from his mouth, Koyomi knew... he fucked up, Tsukihi was set off on one of her trademark tantrums. Koyomi did his best to tune out her wailing, flinging various profanities in his general direction with no end in sight. Silently asking any God in the area to smite this girl down to stop that incessant whining. After Tsukihi was satisfied, her rage sufficiently vented she went back to the television, losing interest in her idiot brother.

'Don't just ignore me after something like that!' He shouted in annoyance, but it was already to late, with Tsukihi being immersed in the wonders of TV all too quickly.

Why couldn't he be blessed with someone quieter or easier as a sister he pondered to himself after being subjected to that verbal beating, but no he had to have the 'fire sisters' fighting for justice every other day while he cleans up the fucking supernatural messes of half the country.

 _I do suppose I have another sister..._

His mind began to wander as he thought about the other girl that called him Oniichan. Recalling the last time he saw the brown haired girl. Specifically, the invitation to her house.

 _That's it!_ He shouted inwardly, an escape from his boredom and his troublesome family.

 _It's been a while as well, could be a good chance to check up on her, she does see me as a brother, better to act like it._

Cellphone in hand, Koyomi eagerly dialed Sengoku's number. After a couple short tones, a frantic, high pitched voice echoed in Koyomi's head undoubtedly belonging to Nadeko Sengoku.

'Hello! This is Sengoku! It's b-been a while Koyomi-oniichan, what's going on?' her nervous tone betraying any confidence she was trying to convey.

'Sorry for the short notice but remember when you invited me over? I was thinking we could do that today, if it's not too much trouble for you.'

He had to admit this might look a little sketchy, a senior in highshcool asking a middle school girl if it's okay to come over to her house... many would get the wrong idea. But this was different, Koyomi made promises to himself not to violate her in any way not just for her sake but for his own.

 _Senjougahara..._ he shuddered at the very thought of his girlfriend finding out about this little visit, let alone if he did anything perverted as a little joke. The colour drained from his face at what she might do to him. He owed Shinobu so much for this immortal body.

'Today! Today! Today! I'm VERY busy every day but today! It has to be today!' The uncharacteristic excitability of her Sengoku's tone pulled Koyomi out of his imagined torture at Senjougahara's hands. Bringing a slight smirk to his face.

'I suppose today's our only option then' he announced with a smile.

'Today then' Sengoku replied excitedly, her heart beating so hard she thought it was going to shoot out of her chest.

 _Today,_ she thought, _Koyomi-oniichan will be mine, I need to do what all those magazines said... be assertive, in control, show off... your assets._

Sengoku grew redder and redder going over her plans.

 _What will he think? Where will it all go from there?_ These questions spun round and round Sengoku's head as she panned out the days events, an ear to ear grin forming on her face. _Finally the boy I..._ _Like? Love? How do I feel about him!?_ Complicated feelings swirled around in Sengoku's head feeling like it was going to explode.

Oblivious to the meticulously laid out plans Sengoku had for him, Koyomi entered the living room to collect Tsukuhi for their little visit. However Koyomi much to his chagrin was immediately turned down flat.

'Just go by yourself'

'She's your friend you idiot girl, don't you want to see her again?' _I'm pretty sure she needs the support of a friend right now too after what she's been through..._ Koyomi contemplated.

'I won't interfere with a friend's feeling of love' Tsukuhi retorted confidently

'What are you saying?!'

This damn girl, Koyomi thought, I'm taking her to see a beloved childhood friend and all she can give me is a stupid excuse like that? What's that even supposed to mean? His cheeks reddening slightly at the implications of that latter statement, _she couldn't mean... no, absolutely not._

'Don't worry I'll look after the house while your gone'

Realizing his sister wouldn't budge he left the house flustered and made his way to Sengoku's address.

All things considered Koyomi was... fairly worried. He had a lot of self-control sure but... Tsukihi was there to ensure nothing perverted could end up happening even by chance!. Could he rely on himself if a chance for a sneaky grope came along? Inhaling deeply and taking a great stride forward Koyomi announced to the heavens...

 **'** THIS GIRL WILL NOT BE MOLESTED IN ANY WAY!' _Heh, Sengoku must be so glad to have a great role model like me._

Ducking through the narrow streets and alleys on his way to Sengoku's, Koyomi was completely ignorant of a certain purple-haired Tsundere who was distracted from her shopping by a suspiciously out of place boyfriend.

Senjougahara Hitagi's groceries would have to wait, for she had a pressing matter to attend too.

A sickening chill went down Koyomi's spine.

 **Well that does it for the first chapter... Pretty average I know, pretty much a regurgitation of the 1st Nisemonogatari episode I know... I'm new okay and I needed a good basis for a Koyomi x Sengoku fic. Well hopefully things get spicier in the next chapter. I hope I did enough to make you laugh at least. :P**

 **P/M me or review to flame or criticize my fic, anything helps tbh. Thanks for reading :D**


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